Control of the Czochraski crystal growth process-almost disturbance decoupling with global asymptotic stability

The nonlinear heat-melt dynamics of a Czochralski crystal growth process is identified to be in the global normal form with globally, asymptotically stable zero dynamics. Nonlinear feedback laws are then constructed that achieve almost disturbance decoupling with global asymptotic stability at a desired operating point. The design relies on the recent developments in nonlinear control theory, and is in contrast with traditional crystal growth process control design methods which are based on linearization through Taylor series expansion and hence always result in stabilization results with unknown (possibly small) basin of attraction.